INS spokesmen say they suspect the youngster was brought to this country for sale to Americans.

The smuggling plot backfired when officers at a customs checkpoint determined his passport had been altered--the boy`s photo was substituted for the original owner`s picture, the expiration date was changed on a tourist visa and other changes were made on a page containing vital statistics.

Edwin is staying at a Salvation Army shelter in Miami`s Little Havana district, waiting for his fate to be decided.

INS District Director Perry Rivkind said Edwin was accompanied from Panama to Miami by a man the boy said was his uncle, Lucio Guerra. Customs agents questioned Guerra last Wednesday, but released him because he is a U.S. citizen.

Rivkind said at least one woman who claimed to be the boy`s mother has appeared at immigration offices, but she quickly disappeared. Four men have called INS offices, claiming to be relatives, but none would leave his name or phone number.

Edwin at first denied that the woman who visited him briefly Thursday was his mother. He then claimed that she was.

``She told me we were going back to Panama,`` Edwin said. ``She said I had to go alone to Panama . . . she will be waiting for me. If she is not waiting, I will have to take a taxi home.``

Rivkind said INS would not release Edwin unless his mother comes forward to claim him.